Answer: 57 in.
Step-by-step explanation:
When two quantities x and y are directly proportional , then the equation to show direct proportion is given y :-
\(\dfrac{x_1}{y_1}=\dfrac{x_2}{y_2}\) (1)
Given : The circumference of a circle varies directly with its radius.
Let c be the circumference of a circle with a radius of 9 in.
If the circumference of a circle with a radius of 1.5 inches is 9.42 in, then from (1) we have
\(\dfrac{c}{9}=\dfrac{9.42}{1.5}\\\\\Rightarrow\ c=\dfrac{9.42}{1.5}\times9=56.52\approx57\ in.\)
Hence, the circumference of a circle with a radius of 9 in is approximately 57 in.
